Body heat from customers enters into the HVAC calculations. Relaxing, our bodies emit about 350 BTU/hr per person. In cold weather, the crowd in the theater heats their building for free - while paying for the privilege of being there.
Of course in the summer, it's that much more energy that must be removed to keep the theater cool.
Two projects in Europe are using geothermal systems to make the most out of the body heat from commuting crowds.
Sam Jones, on This Big City, writes that the Swedish realtor Jernhusen is investing in renovations of Stockholm Central Station, which will include a geothermal system that captures the body heat from the station’s 250,000 daily commuters to use in nearby offices.
Heat exchangers in the ventilation system will convert surplus low-grade body heat into hot water, which will then be pumped to heat office space in the nearby Kungsbrohuset building, also owned by Jernhusen. The plans, due for completion in June 2012, also include the replacement of all lighting in the station with LEDs, with the aim of obtaining Green Building certification.
The system could reduce the energy costs of the office block by up to 25% – a significant saving given Sweden’s cold winters and costly gas. The common ownership of the two buildings makes the transfer of energy a clear win, but – says Klas Johnasson, one of the developers – if real estate owners collaborate, there’s no reason why the project could not be replicated on a commercial basis.
A similar project is underway at the Paris Metro’s Rambuteau station. While this project will generate heat from commuters, it will also use heat from the moving trains to provide heating for a nearby public housing project.
These projects are great because they’re gathering energy that would otherwise be wasted. But they are also only practical in dense, walkable cities where crowds are normal and the harnessed energy doesn’t need to travel far. So is there hope to see this technology on a larger scale?
Forum for the Future’s Head of Built Environment, Martin Hunt, notes that “Geothermal technologies have been around for a long time and are commercially viable. It looks like this application of heat recapture technology will only make sense in busy public spaces, but if the numbers stack up I can see it could be used on a wider scale.”
Photo: Wikimedia Commons
